testLarge2ByteLiteralLengthAndCopyOffset() — netty Function Reference

Source Code

codec-compression/src/test/java/io/netty/handler/codec/compression/SnappyTest.java lines 326–359

    @Test
    public void testLarge2ByteLiteralLengthAndCopyOffset() {
        ByteBuf compressed = Unpooled.buffer();
        ByteBuf actualDecompressed = Unpooled.buffer();
        ByteBuf expectedDecompressed = Unpooled.buffer().writeByte(0x01).writeZero(0x8000).writeByte(0x01);
        try {
            // Generate a Snappy-encoded buffer that can only be decompressed correctly if
            // the decoder treats 2-byte literal lengths and 2-byte copy offsets as unsigned values.

            // Write preamble, uncompressed content length (0x8002) encoded as varint.
            compressed.writeByte(0x82).writeByte(0x80).writeByte(0x02);

            // Write a literal consisting of 0x01 followed by 0x8000 zeroes.
            // The total length of this literal is 0x8001, which gets encoded as 0x8000 (length - 1).
            // This length was selected because the encoded form is one larger than the maximum value
            // representable using a signed 16-bit integer, and we want to assert the decoder is reading
            // the length as an unsigned value.
            compressed.writeByte(61 << 2); // tag for LITERAL with a 2-byte length
            compressed.writeShortLE(0x8000); // length - 1
            compressed.writeByte(0x01).writeZero(0x8000); // literal content

            // Similarly, for a 2-byte copy operation we want to ensure the offset is treated as unsigned.
            // Copy the initial 0x01 which was written 0x8001 bytes back in the stream.
            compressed.writeByte(0x02); // tag for COPY with 2-byte offset, length = 1
            compressed.writeShortLE(0x8001); // offset

            snappy.decode(compressed, actualDecompressed);
            assertEquals(expectedDecompressed, actualDecompressed);
        } finally {
            compressed.release();
            actualDecompressed.release();
            expectedDecompressed.release();
        }
    }